Upper Lip Burstone Line: What It Measures and How FaceIQ Labs Reads It

Key facts

• The Upper Lip Burstone Line is the upper lip's signed perpendicular distance from a line running from the nose base (subnasale) to the soft-tissue chin.
• It is calculated as the perpendicular upper-lip distance to the Burstone-line multiplied by the photo scale.
• In FaceIQ Labs, a negative value means the lip lies in front of the line, a positive value means it lies behind the line, and zero means contact.
• FaceIQ Labs scales photos using an assumed 190 mm hairline-to-chin height, so millimeter values are estimates, not calibrated physical measurements.
• A change in chin position can change the result without the lip moving, because the chin is one endpoint of the reference line.
• A negative value is not automatically a poor result.
• The idea draws on Burstone's 1967 clinical work on lip posture, which used the nasal base and soft-tissue chin as a profile reference.
• The worked example values (+2 mm, 0, −1 mm) explain the calculation and are not a target range.
• FaceIQ Labs states that its score weights and reference ranges are model settings and that the cited papers do not collectively validate its scoring system.

What does the Upper Lip Burstone Line measure?

The Upper Lip Burstone Line is a side-view Harmony measurement in FaceIQ Labs. It is the perpendicular distance from the upper lip to a line running from the nose base (subnasale) to the soft-tissue chin, multiplied by the photo scale and reported in estimated millimeters. In FaceIQ Labs' guides, nasion means the nasal root, subnasale the nose base, and pogonion the most forward chin point. Frankfort refers to the direction from the ear-opening landmark to the lower orbital landmark.

How does FaceIQ Labs read a negative or positive Upper Lip Burstone Line result?

• Negative: the upper lip lies in front of the nose-base-to-chin line.
• Positive: the upper lip lies behind the line.
• Zero: the upper lip touches the line.
• This sign convention describes FaceIQ Labs' result, and a negative value is not automatically a poor result.

Why does the Upper Lip Burstone Line matter?

The Upper Lip Burstone Line places the upper lip within the surrounding profile in FaceIQ Labs' Harmony analysis. The result depends on lip position and on the reference endpoints, so a change in chin position can change the value without the lip changing. Using the nasal base reduces nose-tip influence but still depends on chin and base position.

Where does the Burstone Line idea come from?

The Upper Lip Burstone Line draws on Burstone's clinical work on lip posture, which used the nasal base and soft-tissue chin as a profile reference. FaceIQ Labs notes that avoiding the nose tip changes which surrounding features influence the line. Burstone's paper on lip posture and treatment planning was published in 1967.

What does a worked example of the Upper Lip Burstone Line look like?

In FaceIQ Labs' worked example, an upper lip 2 estimated mm behind the Burstone-line reads +2 mm. Moving the lip onto that unchanged line gives zero, and a lip 1 mm in front of the line gives −1 mm. These values only explain the calculation; they are not a target range and not measurements of the schematic.

Why are the Upper Lip Burstone Line millimeter values only estimates?

FaceIQ Labs scales each photo using an assumed 190 mm hairline-to-chin height, so Upper Lip Burstone Line values in millimeters are estimates, not calibrated physical measurements. Because the scale rests on an assumed height rather than a measured one, the numbers are best read as approximate rather than exact.

Where does the Upper Lip Burstone Line fit in the FaceIQ Labs Harmony score?

The Upper Lip Burstone Line is one of the facial ratios and angles in FaceIQ Labs' Harmony pillar, which measures 70+ ratios and angles against ideal ranges adjusted for gender and ethnicity. This measurement comes from the side photo. Harmony is weighted roughly 60% from the front photo and 40% from the side photo, and side photos are standardized to the Frankfort horizontal plane during landmarking.

What research does FaceIQ Labs cite for the Upper Lip Burstone Line?

FaceIQ Labs lists two sources: Burstone's 1967 paper "Lip posture and its significance in treatment planning," and a 2011 paper by Buschang, Fretty & Campbell on profile planes and lower lip position. The 2011 study compared five lip reference lines, including Steiner's S-line, in 79 orthodontic patients and found that moving reference points can make a lip appear to move backward even when it moves forward. FaceIQ Labs says its score weights and reference ranges are model settings, and that the papers do not collectively validate its scoring system.

What other Harmony measurements relate to the Upper Lip Burstone Line?

• Lower Lip Burstone Line
• Upper Lip S-Line Position
• Lower Lip S-Line Position
• Upper Lip E-Line Position
• Lower Lip E-Line Position
• Holdaway H Line
• Mentolabial Angle

Frequently asked questions

What is the Upper Lip Burstone Line in FaceIQ Labs?

It is a side-view Harmony measurement of the upper lip's signed perpendicular distance from a line running from the nose base (subnasale) to the soft-tissue chin, scaled to an estimated millimeter value.

Does a negative Upper Lip Burstone Line value mean a bad result?

No. FaceIQ Labs states that a negative value, meaning the lip lies in front of the line, is not automatically a poor result, because the value depends on lip position and on where the nose base and chin endpoints fall.

Why can my Upper Lip Burstone Line change if only my chin position changes?

The reference line runs from the nose base to the soft-tissue chin, so a change in chin position moves the line itself. That can change the result even if the upper lip has not moved.

Are the Upper Lip Burstone Line millimeter values exact?

No. FaceIQ Labs scales photos using an assumed 190 mm hairline-to-chin height, so the values are estimates rather than calibrated physical measurements.

What does zero mean for the Upper Lip Burstone Line?

Zero means the upper lip touches the Burstone-line. Positive values mean the lip is behind the line, and negative values mean it is in front.

Is the example value of +2 mm a target?

No. FaceIQ Labs says the example values (+2 mm, zero and −1 mm) only explain the calculation and are not a target range.